1. Field of the Invention
Various embodiments of the invention relate to a removable top fill water tank for use in association with an operating unit, and in particular for use in a humidifier.
2. Description of the Related Art
Portable humidifiers provide an economical appliance for improving indoor environmental conditions. Small humidifiers are convenient because they can be easily moved or stored. Such convenience is especially pertinent to locations with changing climates. Humidifiers can be used when the air is dry and stored away when the air is humid.
Typical portable humidifiers are designed to operate most efficiently with a specific amount of water. For example, wick-type humidifiers have a certain water level that is optimal for operation of the humidifier. Wick-type humidifiers typically include a wick and a fan. The wick sits in a pool of water held in a tray and the water is absorbed by the wick. Thus, if the water level is too low, the air blows through less of the dampened wick, resulting in less water output. On the other hand, if the water level is too high, the air is not able to blow over enough of the wick to capture a significant amount of water.
As the humidifier operates, the water level decreases. In order to keep the water at the optimum level, a water tank is utilized. The water tank continuously feeds water to the humidifier to maintain an optimal water level. The water tank also enables the humidifier to operate over extended periods of time by replenishing the water in the tray of the humidifier.
A typical humidifier water tank is a sealed container with an outlet valve in the bottom. The outlet valve is usually spring-loaded and opens upon placement of the tank onto the tray. When the tank is first placed over the empty water tray of the humidifier the water flows down into the tray. As the water leaves the tank, the pressure at the top of the sealed tank decreases. The pressure continues to decrease as water leaves the tank until the pressure is low enough to hold the water in the tank. Air is then sucked into the tank restoring the pressure and allowing the water to flow out again. This process continues with water flowing out of the tank in cycles while the tray is filled. Once the water level in the tray reaches its maximum height, it covers the outlet of the water tank. Consequently, air is prevented from being sucked into the tank because the air path to the tank outlet is blocked by the water in the tray. This keeps the pressure in the water tank low and stops the water from flowing out. The water flow does not resume until the water level in the tank has fallen to a point that allows air to be sucked into the tank in order to restore the pressure therein.
Humidifier water tanks include openings so that they can be refilled. The opening has a cap such that it can be opened and closed. Typically, the opening and its cap are provided in the bottom of the tank. In some cases, the outlet valve is integrated in the cap of the opening. Having the tank opening in the bottom of the tank requires the user to remove the water tank from the humidifier and flip it over before pouring more water into the tank. Many users find this to be a nuisance, especially when refilling repeatedly in a short period of time or when the tank is large. However, such tanks are intended to be operated this way. If the opening were provided in the top of the tank, the user would still be required to remove the tank before refilling it. Removing the tank closes the spring-loaded outlet valve, and the cap can then be removed and the tank refilled. However, at some point the user would undoubtedly attempt to fill the tank while it was placed on the tray. As soon as the user opened the cap enough to allow air to pass into the tank, the tank would effectively become a hose, with an opening in the top, and an opening in the bottom at the spring-loaded outlet valve. The water would continuously flow out of the tank, overflow the tray and making a mess. That is, by removing the cap the low back-pressure in the tank is destroyed and thus cannot hold the water back within the tank. Nonetheless, many users find water tanks with openings in their bottoms to be a nuisance.
There is thus a need for a removable tank which can be filled from the top either while remaining on the operating unit, e.g., a humidifier, or after being removed from the operating unit.